Aircraft quality wire is manufactured to MIL-W-22759/16 specs. It features standard tin-plated copper conductor with Tefzel insulation.
18 gauge white wire with yellow stripe
18awg stranded white-yellow Tefzel (ETFE)insulated M22759/16-18 wire.
Wire is rated for 600volts rms & 150 degrees C.
FAA AC43.13-1B recommends 10 amp CB protection for 18awg wire.